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cputlb: Support generating CPU exceptions on memory transaction failures

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Call the new cpu_transaction_failed() hook at the places where
CPU generated code interacts with the memory system:
 io_readx()
 io_writex()
 get_page_addr_code()

Any access from C code (eg via cpu_physical_memory_rw(),
address_space_rw(), ld/st_*_phys()) will *not* trigger CPU exceptions
via cpu_transaction_failed().  Handling for transactions failures for
this kind of call should be done by using a function which returns a
MemTxResult and treating the failure case appropriately in the
calling code.

In an ideal world we would not generate CPU exceptions for
instruction fetch failures in get_page_addr_code() but instead wait
until the code translation process tried a load and it failed;
however that change would require too great a restructuring and
redesign to attempt at this point.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
This commit is contained in:
Peter Maydell 2017-09-04 15:21:55 +01:00
parent 0dff0939f6
commit 04e3aabde3
2 changed files with 32 additions and 4 deletions
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32
accel/tcg/cputlb.c
View file

@ -747,6 +747,7 @@ static inline ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr)
}
static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
int mmu_idx,
target_ulong addr, uintptr_t retaddr, int size)
{
CPUState *cpu = ENV_GET_CPU(env);
@ -754,6 +755,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs);
uint64_t val;
bool locked = false;
MemTxResult r;
physaddr = (physaddr & TARGET_PAGE_MASK) + addr;
cpu->mem_io_pc = retaddr;
@ -767,7 +769,12 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
qemu_mutex_lock_iothread();
locked = true;
}
memory_region_dispatch_read(mr, physaddr, &val, size, iotlbentry->attrs);
r = memory_region_dispatch_read(mr, physaddr,
&val, size, iotlbentry->attrs);
if (r != MEMTX_OK) {
cpu_transaction_failed(cpu, physaddr, addr, size, MMU_DATA_LOAD,
mmu_idx, iotlbentry->attrs, r, retaddr);
}
if (locked) {
qemu_mutex_unlock_iothread();
}
@ -776,6 +783,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
}
static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
int mmu_idx,
uint64_t val, target_ulong addr,
uintptr_t retaddr, int size)
{
@ -783,6 +791,7 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
hwaddr physaddr = iotlbentry->addr;
MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs);
bool locked = false;
MemTxResult r;
physaddr = (physaddr & TARGET_PAGE_MASK) + addr;
if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) {
@ -795,7 +804,12 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
qemu_mutex_lock_iothread();
locked = true;
}
memory_region_dispatch_write(mr, physaddr, val, size, iotlbentry->attrs);
r = memory_region_dispatch_write(mr, physaddr,
val, size, iotlbentry->attrs);
if (r != MEMTX_OK) {
cpu_transaction_failed(cpu, physaddr, addr, size, MMU_DATA_STORE,
mmu_idx, iotlbentry->attrs, r, retaddr);
}
if (locked) {
qemu_mutex_unlock_iothread();
}
@ -845,6 +859,7 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
MemoryRegion *mr;
CPUState *cpu = ENV_GET_CPU(env);
CPUIOTLBEntry *iotlbentry;
hwaddr physaddr;
index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
mmu_idx = cpu_mmu_index(env, true);
@ -868,6 +883,19 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
}
qemu_mutex_unlock_iothread();
/* Give the new-style cpu_transaction_failed() hook first chance
* to handle this.
* This is not the ideal place to detect and generate CPU
* exceptions for instruction fetch failure (for instance
* we don't know the length of the access that the CPU would
* use, and it would be better to go ahead and try the access
* and use the MemTXResult it produced). However it is the
* simplest place we have currently available for the check.
*/
physaddr = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
cpu_transaction_failed(cpu, physaddr, addr, 0, MMU_INST_FETCH, mmu_idx,
iotlbentry->attrs, MEMTX_DECODE_ERROR, 0);
cpu_unassigned_access(cpu, addr, false, true, 0, 4);
/* The CPU's unassigned access hook might have longjumped out
* with an exception. If it didn't (or there was no hook) then

4
softmmu_template.h
View file

@ -101,7 +101,7 @@ static inline DATA_TYPE glue(io_read, SUFFIX)(CPUArchState *env,
uintptr_t retaddr)
{
CPUIOTLBEntry *iotlbentry = &env->iotlb[mmu_idx][index];
return io_readx(env, iotlbentry, addr, retaddr, DATA_SIZE);
return io_readx(env, iotlbentry, mmu_idx, addr, retaddr, DATA_SIZE);
}
#endif
@ -262,7 +262,7 @@ static inline void glue(io_write, SUFFIX)(CPUArchState *env,
uintptr_t retaddr)
{
CPUIOTLBEntry *iotlbentry = &env->iotlb[mmu_idx][index];
return io_writex(env, iotlbentry, val, addr, retaddr, DATA_SIZE);
return io_writex(env, iotlbentry, mmu_idx, val, addr, retaddr, DATA_SIZE);
}
void helper_le_st_name(CPUArchState *env, target_ulong addr, DATA_TYPE val,